(1 of )FILE - This undated photo provided by Eric Paddock shows his brother, Las Vegas gunman Stephen Paddock. On Sunday, Oct. 1, 2017, Stephen Paddock opened fire on the Route 91 Harvest Festival killing dozens and wounding hundreds. Authorities trying to piece together the final days before Stephen Paddock unleashed his arsenal of powerful firearms on country music fans on the Las Vegas Strip have at least one potential trove of information: his gambling habits. Gaming regulators say they’re sorting through documents that can include suspicious transaction or currency reports. (Courtesy of Eric Paddock via AP)

(2 of )Part of Reno Ave. near South Las Vegas Blvd is blocked with police tape in the aftermath of a mass shooting Wednesday, Oct. 4, 2017, in Las Vegas. A gunman opened fire on an outdoor music concert on Sunday. It was the deadliest mass shooting in modern U.S. history, with dozens killed and hundreds injured, some by gunfire, some during the chaotic escape. (AP Photo/Marcio Jose Sanchez)

(3 of ) People run from the Route 91 Harvest country music festival after gunfire was heard on October 1, 2017 in Las Vegas, Nevada. (Photo by David Becker/Getty Images)

(4 of ) A wounded person is walked in on a wheelbarrow as Las Vegas police respond during an active shooter situation on the Las Vegas Stirp in Las Vegas Sunday, Oct. 1, 2017. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (Chase Stevens/Las Vegas Review-Journal via AP)

(5 of ) Police officers advise people to take cover near the scene of a shooting near the Mandalay Bay resort and casino on the Las Vegas Strip, Sunday, Oct. 1, 2017, in Las Vegas. (AP Photo/John Locher)

(7 of ) People assist a wounded woman at the Tropicana during an active shooter situation on the Las Vegas Stirp in Las Vegas Sunday, Oct. 1, 2017. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (Chase Stevens/Las Vegas Review-Journal via AP)

(8 of ) Medics treat the wounded as Las Vegas police respond during an active shooter situation on the Las Vegas Stirp in Las Vegas Sunday, Oct. 1, 2017. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (Chase Stevens/Las Vegas Review-Journal via AP)

(9 of ) Police officers stand at the scene of a shooting near the Mandalay Bay resort and casino on the Las Vegas Strip, Sunday, Oct. 1, 2017, in Las Vegas. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (AP Photo/John Locher)

(10 of ) Police officers and medical personnel stand at the scene of a shooting near the Mandalay Bay resort and casino on the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (AP Photo/John Locher)

(11 of ) A police officer takes cover behind a truck at the scene of a shooting near the Mandalay Bay resort and casino on the Las Vegas Strip, Sunday, Oct. 1, 2017, in Las Vegas. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (AP Photo/John Locher)

(12 of ) Police run to cover at the scene of a shooting near the Mandalay Bay resort and casino on the Las Vegas Strip, Sunday, Oct. 1, 2017, in Las Vegas. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (AP Photo/John Locher)

(13 of ) A woman sits on a curb at the scene of a shooting outside of a music festival along the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (AP Photo/John Locher)

(14 of ) People wait as the Tropicana Las Vegas goes on lockdown during an active shooter situation on the Las Vegas Strip in Las Vegas on Sunday, Oct. 1, 2017. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (Chase Stevens/Las Vegas Review-Journal via AP)

(15 of ) People are searched by Las Vegas police at the Tropicana Las Vegas during an active shooter situation on the Las Vegas Strip on Sunday, Oct. 1, 2017. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (Chase Stevens/Las Vegas Review-Journal via AP)

(16 of ) A wounded woman is moved outside the Tropicana during an active shooter situation on the Las Vegas Strip in Las Vegas Sunday, Oct. 1, 2017. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (Chase Stevens/Las Vegas Review-Journal via AP)

(17 of ) A man waits during lockdown at the Tropicana Las Vegas during an active shooter situation on the Las Vegas Strip Sunday, Oct. 1, 2017. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (Chase Stevens/Las Vegas Review-Journal via AP)

(18 of ) In this Sunday, Oct. 1, 2017 frame from video, people leave the scene of a deadly shooting in Las Vegas. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (Shawn Kilgore via AP)

(19 of ) Drapes billow out of broken windows at the Mandalay Bay resort and casino Monday, Oct. 2, 2017, on the Las Vegas Strip following a deadly shooting at a music festival in Las Vegas. A gunman was found dead inside a hotel room. (AP Photo/John Locher)

(20 of ) Drapes billow out of broken windows at the Mandalay Bay resort and casino Monday, Oct. 2, 2017, on the Las Vegas Strip following a deadly shooting at a music festival in Las Vegas. A gunman was found dead inside a hotel room. (AP Photo/John Locher)

(21 of ) Las Vegas police sweep through a convention center area during a lockdown Monday, Oct. 2, 2017, at the Tropicana Las Vegas following an active shooter situation on the Las Vegas Strip. Multiple victims were transported to hospitals after a deadly shooting late Sunday at a music festival on the Las Vegas Strip. (Chase Stevens/Las Vegas Review-Journal via AP)

(22 of ) The main stage at the Route 91 Harvest Music Festival sits in the background as Las Vegas police investigate early Monday, Oct. 2, 2017, after a deadly shooting at the venue in Las Vegas. (Chase Stevens/Las Vegas Review-Journal via AP)

(23 of ) Las Vegas police and emergency vehicles sit on scene following a deadly shooting at a music festival on the Las Vegas Strip early Monday, Oct. 2, 2017. (Chase Stevens/Las Vegas Review-Journal via AP)

(24 of ) People walk near the Las Vegas Strip shortly after sunrise Monday, Oct. 2, 2017, in Las Vegas. A deadly shooting occurred Sunday at a music festival on the Las Vegas Strip. (AP Photo/Ronda Churchill)

(25 of ) A body is covered with a sheet after a mass shooting in which dozens were killed at a music festival on the Las Vegas Strip on Sunday, Oct. 1, 2017. (Steve Marcus/Las Vegas Sun via AP)

(26 of ) A woman speaks on the phone while walking along the Las Vegas Strip near Mandalay Bay hotel and casino Monday, Oct. 2, 2017, in Las Vegas. A mass shooting occurred late night Sunday at a music festival on the Las Vegas Strip. (AP Photo/Ronda Churchill)

(27 of ) Melissah Burke and her husband Stephen, of Seattle, walk along the Las Vegas Strip near Mandalay Bay hotel and casino Monday, Oct. 2, 2017, in Las Vegas. The couple, who were attending the music festival last night where a mass shooting occurred, found refuge in a nearby apartment and casino. (AP Photo/Ronda Churchill)

(28 of ) People load into buses destined to different Strip Casinos following a mass shooting at the Route 91 music festival along the Las Vegas Strip, Monday, Oct. 2, 2017. UNLV's Thomas & Mack Center was opened as a place of refuge. (Yasmina Chavez/Las Vegas Sun via AP)

(29 of ) People wait for their ride outside the Thomas & Mack center, which served as a refuge, following a mass shooting at the Route 91 music festival along the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas. (Yasmina Chavez/Las Vegas Sun via AP)

(30 of ) Metro Police conduct a search on people bringing supplies to the people taking refuge inside the Thomas & Mack following a mass shooting at the Route 91 music festival along the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas. (Yasmina Chavez/Las Vegas Sun via AP)

(31 of ) People embrace after arriving at Metro Headquarters to check on loved ones early Monday, Oct. 2, 2017, after a mass shooting at a music festival on the Las Vegas Strip Sunday. (Yasmina Chavez/Las Vegas Sun via AP)

(33 of ) A woman cries while hiding inside the Sands Corporation plane hangar after a mass shooting in which dozens were killed at the Route 91 Harvest country festival on Sunday, Oct. 1, 2017, in Las Vegas. (Al Powers/Invsion/AP)

(34 of ) Concertgoers embrace as they wait early Monday, Oct. 2, 2017, inside the Sands Corporation plane hangar after a mass shooting in which dozens were killed at the Route 91 Harvest country festival early Sunday. (Al Powers/Invsion/AP)

(35 of ) A young woman checks her phone while hiding inside the Sands Corporation plane hangar after a mass shooting in which dozens were killed at the Route 91 Harvest country festival on Sunday, Oct. 1, 2017, in Las Vegas. (Al Powers/Invision/AP)

(36 of ) A concertgoer makes a phone call early Monday, Oct. 2, 2017, while hiding inside the Sands Corporation plane hangar after a gunman opened fire at the Route 91 Harvest country festival in Las Vegas. (Al Powers/Invision/AP)

(37 of ) Concertgoers check their phones while hiding inside the Sands Corporation plane hangar after a mass shooting in which dozens were killed at Route 91 Harvest Festival on Sunday, Oct. 1, 2017, in Las Vegas. (Al Powers/Invision/AP)

(38 of ) People hold hands in prayer while hiding inside the Sands Corporation plane hangar after a mass shooting in which dozens were killed at the Route 91 Harvest Festival on Sunday, Oct. 1, 2017, in Las Vegas. (Al Powers/Invision/AP)

(39 of ) A woman hides inside the Sands Corporation plane hangar after a mass shooting in which dozens were killed at the Route 91 Harvest Festival on Sunday, Oct. 1, 2017, in Las Vegas. (Al Powers/Invision/AP)

(40 of ) Women make phone calls while taking shelter inside the Sands Corporation plane hangar after a mass shooting in which dozens were killed at Route 91 Harvest Festival on Sunday, Oct. 1, 2017, in Las Vegas. (Al Powers/Invision/AP)

(41 of ) A young woman hides inside the Sands Corporation plane hangar after a gunman opened fire at the Route 91 Harvest Festival on Sunday, Oct. 1, 2017, in Las Vegas. (Photo by Al Powers/Powers Imagery/AP)

(42 of ) People arrive to Thomas & Mack Center via bus after hiding inside the Sands Corporation plane hangar after a mass shooting in which dozens were killed at the Route 91 Harvest country festival on early Monday, Oct. 2, 2017, in Las Vegas. (Al Powers/Invision/AP)

(43 of ) Debris is strewn through the scene of a mass shooting at a music festival near the Mandalay Bay resort and casino on the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas. (AP Photo/John Locher)

(44 of ) A young woman checks her phone while hiding inside the Sands Corporation plane hangar after a mass shooting in which dozens were killed at the Route 91 Harvest Festival on Sunday, Oct. 1, 2017, in Las Vegas. (Al Powers/Invsion/AP)

(45 of ) Moises Flores raises an American flag outside of the Thomas and Mack Center in the aftermath of a mass shooting at a music festival Monday, Oct. 2, 2017, in Las Vegas. (AP Photo/Marcio Jose Sanchez)

(46 of ) Flowers are placed near the scene of a mass shooting at a music festival near the Mandalay Bay resort and casino, top left, on the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas. (AP Photo/Marcio Jose Sanchez)

(47 of ) Investigators load bodies from the scene of a mass shooting at a music festival near the Mandalay Bay resort and casino on the Las Vegas Strip on Monday, Oct. 2, 2017, in Las Vegas. (AP Photo/Chris Carlson)

(49 of ) Two women embrace in front of the concert venue where a mass shooting took place on the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas. (AP Photo/Marcio Jose Sanchez)

(50 of ) Aria James, with back to camera, and Jenna Kerr, from Ventura, Calif, embrace Monday, Oct. 2, 2017, on the Las Vegas Strip near a concert venue where a mass shooting occurred in Las Vegas. Both attended the concert. (AP Photo/Marcio Jose Sanchez)

(51 of ) Reed Broschart, center, hug his girlfriend Aria James on the Las Vegas Strip in the aftermath of a mass shooting at a concert Monday, Oct. 2, 2017, in Las Vegas. The couple, both of Ventura, Calif., attended the concert. (AP Photo/Marcio Jose Sanchez)

(52 of ) Sean Bean, left, of Livermore, Calif., and his girlfriend Katie Kavetski, of San Leandro, Calif., who both attended a concert where a mass shooting occurred, embrace on the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas. (AP Photo/Marcio Jose Sanchez)

(53 of ) Two women embrace outside of a family assistance center Monday, Oct. 2, 2017, in Las Vegas. The makeshift center was set up to help families and others reconnect after the mass shooting on the Las Vegas Strip. (AP Photo/John Locher)

(54 of ) Investigators work the scene Monday, Oct. 2, 2017, after a mass shooting at a music festival near the Mandalay Bay resort and casino on the Las Vegas Strip on Sunday in Las Vegas. (AP Photo/Chris Carlson)

(55 of ) Sean Bolger is comforted by a friend during a vigil at City Hall in Las Vegas, Monday, Oct. 2, 2017. The vigil was held in honor of the over 50 people killed and hundreds injured in a mass shooting at an outdoor music concert late Sunday. (AP Photo/Gregory Bull)

(56 of ) Police tape blocks off the home of Stephen Craig Paddock on Monday, Oct. 2, 2017, in Mesquite, Nev. Paddock killed dozens and injured hundreds on Sunday night when he opened fire at an outdoor country music festival in Las Vegas. Heavily armed police searched Paddock's home Monday. (AP Photo/Chris Carlson)

(57 of ) A woman reacts during a special service at Guardian Angel Cathedral for the mass shooting on the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas. (AP Photo/John Locher)

(58 of ) Maritza Rodriguez, right, embraces Emily Zamora after a special service at Guardian Angel Cathedral for the mass shooting on the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas. (AP Photo/John Locher)

(59 of ) Students from University of Nevada Las Vegas hold a vigil Monday, Oct. 2, 2017, in Las Vegas. A gunman on the 32nd floor of the Mandalay Bay casino hotel rained automatic weapons fire down on the crowd of over 22,000 at an outdoor country music festival Sunday. (AP Photo/Gregory Bull)

(60 of ) Natalynn Rivis, a student at University of Nevada Las Vegas, right, takes part in a vigil Monday, Oct. 2, 2017, in Las Vegas. A gunman on the 32nd floor of the Mandalay Bay casino hotel rained automatic weapons fire down on the crowd of over 22,000 at an outdoor country music festival Sunday. (AP Photo/Gregory Bull)

(61 of ) University of Nevada Las Vegas students Raymond Lloyd, right, and Karla Rodriguez take part in a vigil Monday, Oct. 2, 2017, in Las Vegas. A gunman on the 32nd floor of the Mandalay Bay casino hotel rained automatic weapons fire down on the crowd of over 22,000 at an outdoor country music festival Sunday. (AP Photo/Gregory Bull)

(62 of ) Students from University of Nevada Las Vegas hold a vigil Monday, Oct. 2, 2017, in Las Vegas. A gunman on the 32nd floor of the Mandalay Bay casino hotel rained automatic weapons fire down on the crowd of over 22,000 at an outdoor country music festival Sunday. (AP Photo/Gregory Bull)

(63 of ) Virginia, right, and Natalie Ramos light candles as students from University of Nevada Las Vegas hold a vigil Monday, Oct. 2, 2017, in Las Vegas. A gunman on the 32nd floor of the Mandalay Bay casino hotel rained automatic weapons fire down on the crowd of over 22,000 at an outdoor country music festival Sunday. (AP Photo/Gregory Bull)

(64 of ) Luminaries for victims of the the Sunday evening shooting tragedy in Las Vegas are lit on the front steps of Greene Memorial United Methodist Church surrounded by those brought together in prayer and solidarity on Monday, Oct. 2, 2017, in Roanoke, Va. (Heather Rousseau/The Roanoke Times via AP)

(65 of ) Investigators walk through debris on festival grounds across the street from the Mandalay Bay Resort and Casino on Tuesday, Oct. 3, 2017, in Las Vegas. Authorities said Stephen Craig Paddock broke windows on the casino and began firing with a cache of weapons, killing dozens and injuring hundreds at the festival. (AP Photo/Marcio Jose Sanchez)

(66 of ) Healthcare workers from UMC Hospital in Las Vegas, get free food on Tuesday, Oct. 3, 2017. Hospitals were overflowing with victims of a gunman who fired on a concert from the 32nd floor of a Las Vegas hotel. (AP Photo/Gregory Bull)

Las Vegas gunman may have scoped out other music festivals

KEN RITTER, MICHAEL BALSAMO AND SADIE GURMAN

ASSOCIATED PRESS | October 5, 2017

LAS VEGAS — Investigators are looking into whether gunman Stephen Paddock scoped out bigger music festivals in Las Vegas and Chicago — and perhaps Boston's Fenway Park — before setting up his perch in a casino hotel and raining deadly fire on country music fans.

Paddock booked rooms overlooking the Lollapalooza festival in Chicago in August and the Life Is Beautiful show near the Vegas Strip in late September, according to authorities reconstructing his movements before he undertook the deadliest mass shooting in modern U.S. history.

It was not clear if he contemplated massacres at those sites.

Investigators looking into Paddock also came across mention of Fenway Park, Boston police Lt. Detective Mike McCarthy said, though he provided no further details.

The details came to light as investigators struggled to figure out why the high-stakes gambler opened fire on a crowd of 22,000 Sunday night from the 32nd floor of the Mandalay Bay hotel casino in Las Vegas. He killed 58 people and injured nearly 500 before taking his own life.

A federal official said authorities are looking into the possibility Paddock planned additional attacks, including a car bombing. The official wasn't authorized to discuss the matter publicly and spoke to The Associated Press on condition of anonymity.

Authorities previously disclosed Paddock had 1,600 rounds of ammunition in his car, along with fertilizer that can be used to make explosives and 50 pounds of Tannerite, a substance used in explosive rifle targets.

Investigators have been combing through his background but remain stumped as to his motive.

The profile developed so far is of a "disturbed and dangerous" man who acquired an arsenal over decades, Sheriff Joseph Lombardo said. But investigators have been frustrated to find that he lived a "secret life," Lombardo said, "much of which will never be fully understood."

In other developments:

— In a rare concession on gun control, the National Rifle Association announced its support Thursday for regulating "bump stocks," attachments that can effectively convert semi-automatic rifles into fully automated weapons. Paddock apparently used such devices during the bloodbath.

— The coroner's office in Las Vegas would not release details of its autopsy on Paddock. Some behavioral experts have wondered whether the 64-year-old Paddock suffered from some kind of brain abnormality or had a terminal illness that prompted him to lash out.

The weekend before the massacre, he rented a room through Airbnb at the 21-story Ogden condominiums in downtown Las Vegas and stayed there during a music festival below that included Chance the Rapper, Muse, Lorde and Blink-182.

"Reasons that ran through Paddock's mind is unknown, but it was directly at the same time as Life Is Beautiful," the sheriff said.

Police were reviewing video shot at the high-rise to check Paddock's movements. His renting the condo was curious because as a high-roller, he could have easily gotten a free room at one of the casino hotels on the Vegas Strip.

In early August, Paddock booked a room at Chicago's 21-story Blackstone Hotel that overlooked the park where the Lollapalooza alternative music festival was being held, though there's no evidence he actually stayed there, a law enforcement official said Thursday.

The official was not authorized to discuss the case publicly and spoke on condition of anonymity after being briefed on the investigation.

The hotel confirmed a Stephen Paddock made a reservation but said he never checked in.